Exchangeable knife blade



Dec. 3, 1940. FEH$E 2,223,342

EXCHANGEABLE KNIFE BLADE Filed July 1, 1938 INVENTOR BY Han; 22kg:-

1113; ATTORNEY Patented Dec. 3, 1940 UNITED STATES PATENT OFFICE EXCHANGEABLE KNIFE BLADE I r l Hans Fehse, Brooklyn, N. Y.

' Application July 1, 1938, Serial No. 216,971

3 Claims.

This invention relates to knives or cutters in general, and especially to the type of cutters used in relatively heavy cutting devices.

. Inheavy cutting devices, such as paper cut- 5 ters, the blade employed is subjected to a good deal of wear and strain, in consequence of which a very fine quality of steel must be used to maintain' a sharp cutting edge. Usually, the dimensions of heavy cutters are so large that the blades used therein represent a very substantial investment. High-grade steel used for blades must be sufiiciently hardened in order to maintain the edge for an extended period of time. Due to this hardening, the blades become relatively brittle and are likely to crack or break. In the event that the blades break, which is very often the case; the replacement of such broken knives becomesjcostly, which directly reflects upon the price of the material cut.

For all practical purposes, the most important portion of the blade is that which is equipped with the cutting edge or that part which first engages the work to be cut. That portion must be of a very fine grade of steel, so as to hold the edgeand so that it may be readily resharpened when becoming dull.

The present invention has for its principal object the provision of an elongated knife blade or cutter the length of which'far exceeds its width to "or breadth, and wherein the cutting portion of the blade may be relatively narrow or short, whereas the" body of the blade above the cutting edge may be made as wide or high as is practical or desirable for the attachment of the blade to the 35 bladeholder.

Another object of the present invention resides in the connection between the cutting portion of the, blade, madepreferably of superior steel, such as high-speed or high carbon steel, and the upper 40 body of the blade, made preferably of inferior,

less expensive material.

Another object of this invention is to provide an end stop at one end of the combination blade,

so as to prevent the movement of one blade mem- 45 her relative to the other blade member in one direction. This is especially necessary in View of the fact that the usual movement of the cutter is a slicing motion, while the blade descends. Consequently, there is a tendency of the cutting 50 member of the blade to slide out from the upper body thereof.

The foregoing and still further objects and important advantages of the present invention will become more fully apparent from the ensuing description, in connection with the accomblade.

Fig. 3 illustrates a perspective view-of the cutting portion of my combination blade.

Fig. 4 illustrates a modified end stop construction for the blade. 16

Fig. 5 is an end view of the cutting portion of my blade, and v Fig. 6 illustrates another embodiment of the end stop construction for the blade.

Referring now specifically t the drawing, nu- 20 meral l0 denotes the upper member of my blade construction, whereas numeral II denotes the cutting member of my blade, the former being made of relatively inferior, inexpensive steel, while the latter is made of high-grade, and there- 25 fore costly steel. It will be observed from Figs. 2, 3 and 5 that the two members are connected longitudinally by a substantially key-stone shaped dovetail connection, consisting of a male portion I 2 extending upwards from cutting member ll and a corresponding female recess l3 provided in the lower edge of member I0. From the dovetail formation of the male member extends a tongue 14, which is of a substantial construction and which is adapted to enter a corresponding groove l5 provided over the female dovetail portion l3 of member II]. It will be noted that the lower, dovetail portion of the connection is of relatively stout, heavy construction and is somewhat longer than tongue which latter is relatively slender in comparison with dovetail I 2.

This tongue and groove arrangement is intended to stabilize the connection between the two members and to prevent the breaking out of the relatively frail dovetail connection, especially at the weakest points of member ID, as indicated at 5 in Fig. 2. Tongue l4 effectivel prevents a lateral movement of cutting member H relative to body member I 0 of the blade.

Specific attention is invited to the left hand 5 end construction of members l0 and II, constituting eifective stop means for member I I against an outward movement in left hand direction relative to member H]. To achieve this purpose,

I terminate the male portion of the dovetail con- 5 2 nection short from the left hand end of member II, as indicated at H. Correspondingly, I terminate dovetail recess l3 short from the left hand end of member It, as indicated at IS in Fig. 1}. In doing so, I form a step-like stop 19 in member it, which prevents member H from sliding out.

A modified form of the left hand end stop and a connection between the two members is shown in Fig. 4, wherein the step-like extension I9 is recessed at 20, .while a corresponding recess is provided'in cutting member H at 2|. Into this recess as fitted a plate 22,.through which pass, into the bodies of member Ill and II, screws 23 and 24, respectively. These screws hold cutting member I l against a right hand movement relative to member Hi. It is to be noted, of course, that there is usually no appreciable strain exerted against the blade which would havethe I tendency of separating cutting member from body member It in a right hand direction. Therefore, the construction shown in Fig. 4 is merely a double safeguard for holding the two members in fixed relation relative to one another. The cutting portion of my blade, as constructed in accordance with Fi g.- 4, is shown in endview in Fig. 5, in which figure will be observed openings 23 and 24 for receiving, respectively, screws 23 and 24.

Referring to Fig. 6, there is illustrated another embodiment of my stop construction and blade member connection, wherein member III is recessed, as indicated at 25, while member H is recessed at 26. Into these recesses is fitted a block 2'5, which is preferably secured in place by a number of screws 28, extending into the bodies of members [0 and II. Block 2''! serves as an end stop against the movement of member ll relative to member I during the slicing motion of the cutter, and at the same time fixedly holds the two members in their intended position, by means of, screws 28.

From the afore-described construction of my device it becomes quite obvious that it is my intention to produce an effective cutter, wherein the major body of the blade may be made of relatively inexpensive, inferior material, whereas the cuttingmember of the blade is made of fine quality steeL whereby I produce an efficient cutting instrument at a considerable reduction in cost. i

It is also obvious that dueto the combination dovetail and tongue and groove construction of my device, the exchange orreplacement of the most expensive portion of the blade may be readily effected at a minimum cost to the user,

and that due to the tongue and groove construction above, any possible breakageof the dovetail connection is not only greatly minimized, but

practically eliminated. It goeswithout saying,

that while I have shownjin the illustrations a combination cutter intended for heavy duty, the same principle of exchangeable portions with cutting edges for blades is applicable to any other cutting instrumentalities. By the same token, it is obvious that while I have shown specific constructions as to the connections between the two blade members, and also specific constructions of the end stops at one end of the cutter, the application of this principle to other cutting instrumentalities may require changes and improvements, and I, therefore, reserve for myself the right to make such changes and improvements, without departing from the broad scope of my invention as defined in the annexed claims. I

I claim:

I. In an elongated cutter or the like, a member of inferior material, a member of superior material, a longitudinal, interlocking slide connection uniting said members over their entire length, but terminating short from oneend of the members, stop means provided at the short end of the slide connection for preventing the movement inone direction of one member relative to the other, member, said slide connection being substantially of a dovetail construction, in-

cluding a tongue extending from the male member of the connection into a corresponding groove provided in the female member, said tongue and groove serving as safety means for preventing the breakage of the connection through side strains.

2. In an elongated cutter blade construction, wherein the length of the blade far exceeds its breadth, an upper and a lower blade portion, made, respectively, of inferior and superior materials, a straight-line, continuous interlocking slide connection longitudinally uniting the two blade portions over substantially their entire length, startingat one of their extreme ends and terminating at a point a short distance from their other extreme ends, in the space between said point and the terminus of said slide connection a step-like formation depending from the upper blade portion and serving as a stop for the lower blade portion, and fastening means in said step-like formation for immovably securing the two blade portions, against disengagement, said interlocking slide connectionbeing of a key-stone formation and consisting of a relatively stout, lower dovetail-shaped portion and a central projection extending from the latter and being somewhat shorter and far slimmer than said dovetail portion, said projection serving as stabilizer for the connection and as asafety means for preventing the breakage of the latter.

'3. In a cutter blade construction, as set forth in claim 2, said step-like formation beingin the form of a block fixedly secured to the upper blade portion, and said fastening means, passing through said block, being in operative engagement with the slide connection of the lower blade portion.

HANS FE'HSE. 

